The small size of attack drones and their global availability makes them especially attractive to non-state actors, or to nations (Iran in the Saudi case) who wish to arm proxies with effective weapons while maintaining deniability.  In the current Saudi (or a potential United States civil war scenario), with Balkanized ethnic or religious groups mixed across the battle space, it will always be possible for an enemy guerrilla team to get within drone-launching range of their targets.